1. Field of the Invention
This invention relates generally to a vacuum canister. More particularly, the invention relates to a vacuum canister for surgical fluid collection having a large volume and having structural reinforcement members to withstand an application of vacuum to an interior of the canister.
2. Background of the Invention
Currently, vacuum canisters are used to collect and transport fluids that are produced in surgeries and other medical procedures. Vacuum canisters with portals have been used to collect fluids from collection devices by applying a vacuum to one of the portals. Previously, open topped containers were used to collect fluids by gravity flow.
A disadvantage associated with the use of open top containers includes the possibility of spillage and inadvertent contact with contaminated fluids, particularly during transport. Further, open topped containers are not suitable for the collection of fluids by vacuum.
The use of vacuum canisters has previously been impractical because large containers are susceptible to collapse when subjected to vacuum. Smaller containers are not desirable, because they fill quickly and may pose as a distraction to operating room personnel. Smaller canister, e.g., canisters of between 800 and 3,000 cubic centimeters capacity, are particularly unsuitable for surgical procedures that involve large quantities of irrigation fluids, such as arthroscopic and other types surgery. Arthroscopic surgery has been known to utilize an amount of irrigation fluid significantly in excess of 3,000 cc.
A large surface area is one disadvantage associated with large volume canisters. Since pressure forces are directly proportional to surface area, significant forces act on the outside of a large canister when a vacuum or negative pressure is pulled on the inside of the canister. One way to accommodate the large forces is by providing thick walls for the canister. However, thick walled canisters have an undesirably high material cost for their manufacture and may be heavy and difficult for operating room personnel to manipulate.
One solution to the above problems has been proposed in U.S. Pat. No. 6,270,488 to Johnson, et al. for a “Large Volume Medical Fluid Vacuum Collection Canister”. Johnson, et al. teaches a large volume medical fluid vacuum collection canister that includes a blow molded canister body defining a medical fluid receiving cavity. The canister body includes a pair of opposed upstanding sidewalls interconnected by a pair of opposed upstanding end walls, a top wall with an opening and an opposed bottom wall. Each sidewall includes at least one “reentrant beam portion” extending inwardly from opposed sidewall surfaces into a central region of the medical fluid receiving cavity. The “reentrant beams” from opposing sidewalls are disposed in registering alignment so that internal end faces of the beam portions abut in face-to-face relationship when the container is under vacuum to prevent collapse of the container. However, the beam portions also occupy a significant portion of the volume of the container.
Therefore, as can be seen from the above description, a vacuum canister having a relatively large volume and having the structural integrity to avoid collapsing under vacuum pressure is desired. Additionally, it is desirable for the volume of the container to be unoccupied by support members and the like, which decrease the effective volume of the container.